Dynamic configuration of uplink (ul) and downlink (dl) frame resources for a time division duplex (tdd) transmission

ABSTRACT

Technology for a user equipment (UE) operable to perform adaptive time division duplexing (TDD) hybrid automatic repeat request (HARQ)-ACKnowledgement (ACK) reporting is described. The UE can implement an adaptive uplink-downlink (UL-DL) configuration received from an eNodeB. The UE can process a downlink (DL) HARQ reference configuration received from the eNodeB for a serving cell. The DL HARQ reference configuration can be for the implemented adaptive UL-DL configuration. The UE can format HARQ-ACK feedback for transmission on a physical uplink control channel (PUCCH) or physical uplink shared channel (PUSCH) of the serving cell in accordance with the DL HARQ reference configuration.

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/013,520, filed Feb. 2, 2016 with an attorney docket number ofP56655USC, which is a continuation of U.S. patent application Ser. No.14/125,605 filed Dec. 12, 2013 with an attorney docket number ofP56655US, which claims the benefit of U.S. Provisional PatentApplication Ser. No. 61/753,914, filed Jan. 17, 2013 (attorney docketnumber P53504Z), all of which are hereby incorporated in their entiretyby reference.

BACKGROUND

Wireless mobile communication technology uses various standards andprotocols to transmit data between a node (e.g., a transmission stationor a transceiver node) and a wireless device (e.g., a mobile device).Some wireless devices communicate using orthogonal frequency-divisionmultiple access (OFDMA) in a downlink (DL) transmission and singlecarrier frequency division multiple access (SC-FDMA) in an uplink (UL)transmission. Standards and protocols that use orthogonalfrequency-division multiplexing (OFDM) for signal transmission includethe third generation partnership project (3GPP) long term evolution(LTE), the Institute of Electrical and Electronics Engineers (IEEE)802.16 standard (e.g., 802.16e, 802.16m), which is commonly known toindustry groups as WiMAX (Worldwide interoperability for MicrowaveAccess), and the IEEE 802.11 standard, which is commonly known toindustry groups as WiFi.

In 3GPP radio access network (RAN) LTE systems, the node can be acombination of Evolved Universal Terrestrial Radio Access Network(E-UTRAN) Node Bs (also commonly denoted as evolved Node Bs, enhancedNode Bs, eNodeBs, or eNBs) and Radio Network Controllers (RNCs), whichcommunicate with the wireless device, known as a user equipment (UE).The downlink (DL) transmission can be a communication from the node(e.g., eNodeB) to the wireless device (e.g., UE), and the uplink (UL)transmission can be a communication from the wireless device to thenode.

In homogeneous networks, the node, also called a macro node, can providebasic wireless coverage to wireless devices in a cell. The cell can bethe area in which the wireless devices are operable to communicate withthe macro node. Heterogeneous networks (HetNets) can be used to handlethe increased traffic loads on the macro nodes due to increased densityof the cells deployed. HetNets can include a layer of planned high powermacro nodes (or macro-eNBs) overlaid with layers of lower power nodes(small-eNBs, micro-eNBs, pico-eNBs, femto-eNBs, or home eNBs [HeNBs])that can be deployed in a less well planned or even entirelyuncoordinated manner within the coverage area (cell) of a macro node.The lower power nodes (LPNs) can generally be referred to as “low powernodes”, small nodes, or small cells.

The macro node can be used for basic coverage. The low power nodes canbe used to fill coverage holes, to improve capacity in hot-zones or atthe boundaries between the macro nodes' coverage areas, and improveindoor coverage where building structures impede signal transmission.Inter-cell interference coordination (ICIC) or enhanced ICIC (eICIC) maybe used for resource coordination to reduce interference between thenodes, such as macro nodes and low power nodes in a HetNet.

Homogeneous networks or HetNets can use time-division duplexing (TDD) orfrequency-division duplexing (FDD) for DL or UL transmissions.Time-division duplexing (TDD) is an application of time-divisionmultiplexing (TDM) to separate downlink and uplink signals. In TDD,downlink signals and uplink signals may be carried on a same carrierfrequency where the downlink signals use a different time interval fromthe uplink signals, so the downlink signals and the uplink signals donot generate interference for each other. TDM is a type of digitalmultiplexing in which two or more bit streams or signals, such as adownlink or uplink, are transferred apparently simultaneously assub-channels in one communication channel, but are physicallytransmitted on different time resources. In frequency-division duplexing(FDD), an uplink transmission and a downlink transmission can operateusing different frequency carriers. In FDD, DL-UL interference can beavoided because the downlink signals use a different frequency carrierfrom the uplink signals.

BRIEF DESCRIPTION OF THE DRAWINGS

Features and advantages of the disclosure will be apparent from thedetailed description which follows, taken in conjunction with theaccompanying drawings, which together illustrate, by way of example,features of the disclosure; and, wherein:

FIG. 1 illustrates a diagram of dynamic uplink-downlink (UL-DL)reconfiguration usage in a time-division duplexing (TDD) system inaccordance with an example;

FIG. 2 illustrates a diagram of a legacy long term evolution (LTE) framestructure 2 (FS2) with flexible subframe (FlexSF) in accordance with anexample;

FIG. 3 illustrates a table (Table 2) for hybrid automatic repeat request(HARQ) timing for a set of a legacy long term evolution (LTE)uplink-downlink (UL-DL) time-division duplexing (TDD) configurations inaccordance with an example;

FIG. 4 illustrates a diagram of flexible subframes (FlexSFs) in a set oflegacy long term evolution (LTE) uplink-downlink (UL-DL) time-divisionduplexing (TDD) configurations in accordance with an example;

FIG. 5 illustrates a diagram of hybrid automatic repeat request (HARQ)operation for a user equipment (UE) with dynamic uplink-downlink (UL-DL)reconfigurations in accordance with an example;

FIG. 6 depicts a flow chart of a behavioral model for a user equipment(UE) and an evolved Node B (eNB) in a long term evolution (LTE)time-division duplexing (TDD) network with dynamic uplink-downlink(UL-DL) reconfiguration in accordance with an example;

FIG. 7 depicts a flow chart of a method for dynamically reconfiguring anuplink-downlink (UL-DL) time-division duplexing (TDD) configuration byan evolved Node B (eNB) in accordance with an example;

FIG. 8 depicts functionality of computer circuitry of a user equipment(UE) operable for dynamically reconfiguring an uplink-downlink (UL-DL)time-division duplexing (TDD) configuration in accordance with anexample;

FIG. 9 illustrates a block diagram of a node (e.g., eNB) and wirelessdevice (e.g., UE) in accordance with an example; and

FIG. 10 illustrates a diagram of a wireless device (e.g., UE) inaccordance with an example.

Reference will now be made to the exemplary embodiments illustrated, andspecific language will be used herein to describe the same. It willnevertheless be understood that no limitation of the scope of theinvention is thereby intended.

DETAILED DESCRIPTION

Before the present invention is disclosed and described, it is to beunderstood that this invention is not limited to the particularstructures, process steps, or materials disclosed herein, but isextended to equivalents thereof as would be recognized by thoseordinarily skilled in the relevant arts. It should also be understoodthat terminology employed herein is used for the purpose of describingparticular examples only and is not intended to be limiting. The samereference numerals in different drawings represent the same element.Numbers provided in flow charts and processes are provided for clarityin illustrating steps and operations and do not necessarily indicate aparticular order or sequence.

Example Embodiments

An initial overview of technology embodiments is provided below and thenspecific technology embodiments are described in further detail later.This initial summary is intended to aid readers in understanding thetechnology more quickly but is not intended to identify key features oressential features of the technology nor is it intended to limit thescope of the claimed subject matter.

Time division duplex (TDD) can offer flexible deployments without usinga pair of spectrum resources. For TDD deployments, interference betweenuplink (UL) and downlink (DL) transmission including both basestation-to-base station (BS-to-BS) interference and UE-to-UEinterference can be considered when different uplink-downlink (UL-DL)configurations are used among cells in a network.

FIG. 1 illustrates a layered HetNet deployment with different nodetransmission powers using time-division duplexing (TDD). A nodetransmission power can refer to the power generated by a node type, suchas a macro node (e.g., macro evolved Node B (eNB)) in a macro cell andmultiple low power nodes (LPNs or small eNBs) in the respective smallcells. As used herein, a cell can refer to the node or the coverage areaof the node. The macro nodes can transmit at high power level, forexample, approximately 5 watts (W) to 40 W, to cover the macro cell. TheHetNet can be overlaid with low power nodes (LPNs), which may transmitat substantially lower power levels, such as approximately 100milliwatts (mW) to 2 W. In an example, an available transmission powerof the macro node may be at least ten times an available transmissionpower of the low power node. A LPN can be used in hot spots orhot-zones, referring to areas with a high wireless traffic load or highvolume of actively transmitting wireless devices (e.g., user equipments(UEs)). A LPN can be used in a microcell, a picocell, a femtocell,and/or home network. Small Cell0 illustrates downlink traffic heavyusage by the wireless devices (e.g., UEs) and Small Cell1 illustratesuplink traffic heavy usage by the wireless devices. In a FDD example,the macro cell can use frequency bands F1 for DL and F2 for UL, andsmall cells can use frequency bands F3 for DL and F4 for UL. In a TDDexample, frequency band F1 (or F2) can be used for DL and UL by themacro cell and frequency bands F3/F4 can be used for DL and UL by thesmall cells. In another example, the macro cell and small cells can usethe same frequency band F1, F2, F3, or F4

Allowing adaptive UL-DL configurations depending on traffic conditionsin different cells can significantly improve the system performance insome examples. FIG. 1 illustrates an example where different UL-DLconfigurations can be considered in different cells. Networks (e.g.,HetNets or homogeneous networks) can involve a same carrier or differentcarriers deployed by a single operator or different operators in thesame band and employing either a same or different uplink-downlink(UL-DL) configurations. Different UL-DL configurations can be used indifferent cells of the network (e.g., HetNet), and different carriersdeployed by different operators in the same band can be used employingeither the same or different uplink-downlink configurations.Interference may include adjacent channel interference (when differentcarrier frequencies are used) as well as co-channel interference (when asame carrier frequency is used) such as remote node-to-node interference(or BS-to-BS interference or eNB-to-eNB interference).

Various radio access technologies (RAT), such as legacy LTE TDD Release8, 9, 10, or 11 and advance LTE TDD Release 12, can support asymmetricUL-DL allocations by providing seven different semi-staticallyconfigured uplink-downlink configurations (i.e., legacy UL-DL TDDconfigurations). A legacy UL-DL TDD configurations can refer to a UL-DLTDD configurations as described in LTE TDD Release 8, 9, 10, or 11.Table 1 illustrates seven UL-DL configurations used in LTE, where “D”represents a downlink subframe, “S” represents a special subframe, and“U” represents an uplink subframe. In an example, the special subframecan operate or be treated as a downlink subframe.

TABLE 1 Uplink-downlink Subframe number configuration 0 1 2 3 4 5 6 7 89 0 D S U U U D S U U U 1 D S U U D D S U U D 2 D S U D D D S U D D 3 DS U U U D D D D D 4 D S U U D D D D D D 5 D S U D D D D D D D 6 D S U UU D S U U D

As illustrated by Table 1, UL-DL configuration 0 can include 6 uplinksubframes in subframes 2, 3, 4, 7, 8, and 9, and 4 downlink and specialsubframes in subframes 0, 1, 5, and 6; and UL-DL configuration 5 caninclude one uplink subframe in subframe 2, and 9 downlink and specialsubframes in subframes 0, 1, 3-9.

The legacy LTE UL-DL TDD set of configurations can provide DL subframesallocations in the range of 40% to 90%, and UL subframes allocations inthe range of 10% to 60%, as shown in Table 1. A semi-static allocation,at any given time, may not match the instantaneous traffic situation. Amechanism for adapting UL-DL allocation can be based on a systeminformation change procedure, where the UL and DL subframes allocationwithin a radio frame can be reconfigured through system informationbroadcast signaling (e.g., a system information block 1 [SIB1]). Hence,the UL-DL allocation once configured can be expected to varysemi-statically. With a mechanism based on the SIB1, a minimum latencyof approximately 640 milliseconds (ms) can be used for thereconfiguration.

Thus, a legacy LTE network may not adapt to a UL-DL configuration basedon cell specific instantaneous traffic needs. The semi-staticconfiguration of the DL and UL frame resources across the whole networkmay not allow adjusting an amount of the DL and UL resources based oninstantaneous traffic needs. The inability to adjust the DL and ULresources based on instantaneous traffic situations may createrestriction in small cells deployed in a macro cell coverage area, sincetraffic condition in small cells may vary substantially. Dynamicallocation of the number of the DL and UL frame resources can boostperformance of LTE small cells networks operating in the TDD spectrum.

For instance, mechanisms can be used to support dynamic allocation of ULand DL subframes with a lower latency (e.g., 10 ms), such as “FlexibleSubframes” (FlexSF), as shown in FIG. 2. A flexible subframe is capableof changing an uplink-downlink transmission direction for a set oflegacy UL-DL TDD configurations. For example, subframes with a subframeindex 3, 4, 7, 8, and 9 can vary between UL or DL subframes in the sevendifferent semi-statically configured legacy LTE UL-DL TDD configurations(FIG. 4). Subframes 0, 1, 2, 5, and 6 can be referred to as fixedsubframes since the transmission direction can be fixed as primarily anUL subframe (e.g., subframe 2) or a DL subframe (e.g., DL subframes 0and 5, special subframe 1, or DL or special subframe 6) for the sevendifferent semi-statically configured legacy LTE UL-DL TDDconfigurations.

The technology (e.g., methods, computer circuitry, nodes, configurationdevices, processors, transceivers, or UEs) described herein can enabledynamic change of subframe types (e.g., UL or DL) in the legacy UL-DLconfiguration and signaling mechanisms to support dynamic allocation ofDL and UL resources in the LTE physical frame structure. The technologycan be compatible with a legacy LTE network (i.e., LTE Release 8, 9, 10,or 11) and can have minimal impact on legacy terminals (e.g., UEs), andcan provide lower implementation complexity for the dynamic change. Thetechnology can provide a fast adaptation time scale (e.g., 10 ms) fordynamic reconfiguration of DL and UL frame resources in LTE TDD smallcells.

Advanced UEs (e.g., UEs supporting LTE Release 12 features) supportingUL-DL TDD reconfiguration, can dynamically reconfigure thesemi-statically configured legacy LTE UL-DL TDD configurations toanother configuration by configuring the FlexSF to a differenttransmission direction (e.g., UL to DL, or DL to UL). The FlexSFs can betransparent to legacy UEs, using LTE TDD Release 8, 9, 10 or 11, and theUL or DL configuration of the FlexSFs can be changed semi-statically forlegacy UEs through system information block type 1 (SIB1) informationbits. The node can be responsible to properly schedule the datatransmission of legacy UEs to ensure that the corresponding physicaluplink shared channel (PUSCH) and hybrid automatic repeatrequest-acknowledgement (HARQ-ACK) resources of the physical downlinkshared channel (PDSCH) and the PUSCH still are valid even when the TDDconfiguration is changed for an advanced UE supporting FlexSFs.

A downlink signal or channel can include data on a Physical DownlinkShared CHannel (PDSCH) or control information on a Physical DownlinkControl CHannel (PDCCH). A PDCCH (or enhanced PDCCH) can carry a messageknown as Downlink Control Information (DCI), which can includestransmission resource assignments, such as a PDSCH orPUSCH, and othercontrol information for a UE or group of UEs. Many PDCCHs can betransmitted in a subframe. An uplink signal or channel can include dataon a Physical Uplink Shared CHannel (PUSCH) or control information on aPhysical Uplink Control CHannel (PUCCH). Automatic Repeat reQuest is afeedback mechanism whereby a receiving terminal requests retransmissionof packets which are detected to be erroneous. Hybrid ARQ is asimultaneous combination of Automatic Retransmission reQuest (ARQ) andforward error correction (FEC). When HARQ is used and if the errors canbe corrected by FEC then no whole retransmission may be requested,otherwise if the errors can be detected but not corrected, a wholeretransmission can be requested. An ACKnowledgment (ACK) signal can betransmitted to indicate that one or more blocks of data, such as in aPDSCH, have been successfully received and decoded. HARQ-ACK/NegativeACKnowledgment (NACK or NAK) information can include feedback from areceiver to the transmitter in order to acknowledge a correct receptionof a packet or ask for a new retransmission (via NACK or NAK). A PDSCHHARQ can be transmitted in an uplink subframe after a PDSCH in adownlink subframe, and a PUSCH HARQ can be transmitted in a downlinksubframe after a PUSCH in an uplink subframe. In a legacy system, thetiming relation between the DL/UL grant, the DL/UL data allocation, andthe DL/UL HARQ feedbacks may be predetermined.

In legacy LTE, each of the seven semi-statically configured UL-DL TDDconfigurations can have PDSCH HARQ timings corresponding to ULsubframes, and PUSCH scheduling timings and PUSCH HARQ timingscorresponding to DL subframes. For example, Table 2 illustrates thePDSCH HARQ timing for seven UL-DL configurations used in LTE, asillustrated in FIG. 3. A PDSCH transmission can be indicated by thedetection of corresponding PDCCH or a PDCCH indicating downlink SPSrelease within subframe(s) n−k, where kεK and K defined in Table 2 (alsoshown in Table 10.1.3.1-1 3GPP technical specification (TS) 36.213V11.0.0 (2012-09)) is a set of M elements {k₀, k₁, . . . k_(M-1)}depending on the subframe n. For instance, an uplink subframe n in Table2 can be used to transmit PDSCH HARQ-ACK(s) for PDSCH in subframe(s)n−k.

For example, in TDD configuration 1 indicated by the SIB1, a UL subframe2 can provide a PDSCH HARQ-ACK for DL subframes 5 and 6 of a prior radioframe, a UL subframe 3 can provide a PDSCH HARQ-ACK for DL subframe 9 ofthe prior frame, UL subframe 7 can provide a PDSCH HARQ-ACK for DLsubframes 0 and 1 of the prior frame, and UL subframe 8 can provide aPDSCH HARQ-ACK for DL subframe 4 of the prior frame. In an example, atleast four subframes may occur between a downlink subframe and an uplinksubframe to allow for transmission, decoding, and processing of thedownlink transmission, PDCCH, and/or uplink transmission.

Table 3 illustrates the PUSCH scheduling timing for seven UL-DLconfigurations used in LTE. For UL-reference UL/DL configurationsbelonging to {1,2,3,4,5,6} and a normal HARQ operation, the UE can upondetection of a PDCCH or enhanced physical downlink control channels(EPDCCH or ePDCCH) with an uplink DCI format and/or a physical hybridautomatic repeat request (ARQ) indicator channel (PHICH) transmission insubframe n intended for the UE, adjust a corresponding PUSCHtransmission in subframe n+k, with k given in Table 3 (also shown inTable 8-2 3GPP technical specification (TS) 36.213 V11.0.0 (2012-09)),according to the PDCCH/EPDCCH information and the PHICH information.Physical Hybrid ARQ Indicator CHannel (PHICH) is a downlink physicalchannel which carries the HARQ ACK/NACK information indicating whetherthe node has correctly received a transmission on the PUSCH. ForUL-reference UL/DL configuration 0 and normal HARQ operation, a leastsignificant bit (LSB) of the UL index in the DCI format 0/4 can be setto 1 in subframe n or a PHICH can be received in subframe n=0 or 5 inthe resource corresponding to I_(PHICH)=1, or PHICH can be received insubframe n=1 or 6, the UE can adjust the corresponding PUSCHtransmission in subframe n+7.

TABLE 3 TDD UL/DL subframe number n Configuration 0 1 2 3 4 5 6 7 8 9 04 6 4 6 1 6 4 6 4 2 4 4 3 4 4 4 4 4 4 5 4 6 7 7 7 7 5

For example in TDD configuration 1 indicated by the SIB1, a DL subframe1 can schedule a PUSCH in a UL subframe 7, a DL subframe 4 can schedulea PUSCH in a UL subframe 8, a DL subframe 6 can schedule a PUSCH in a ULsubframe 2 of a subsequent radio frame, and a DL subframe 9 can schedulea PUSCH in UL subframe 3 of a subsequent frame. In an example, at leastfour subframes may occur between a downlink subframe and an uplinksubframe to allow for transmission, decoding, and processing of thedownlink transmission, PDCCH, and/or uplink transmission.

Table 4 illustrates the PUSCH HARQ timing for seven UL-DL configurationsused in LTE. For PUSCH transmissions scheduled from serving cell c insubframe n, a UE can determine the corresponding PHICH resource of aserving cell c in subframe n+k_(PHICH), where k_(PHICH) is given inTable 4 (also shown in Table 9.1.2-1 3GPP technical specification (TS)36.213 V11.0.0 (2012-09)).

TABLE 4 TDD UL/DL subframe index n Configuration 0 1 2 3 4 5 6 7 8 9 0 47 6 4 7 6 1 4 6 4 6 2 6 6 3 6 6 6 4 6 6 5 6 6 4 6 6 4 7

For example in TDD configuration 0 indicated by the SIB1, a PUSCHHARQ-ACK for a UL subframe 2 can be transmitted in a DL subframe 6, aPUSCH HARQ-ACK for a UL subframe 3 can be transmitted in a DL subframe9, a PUSCH HARQ-ACK for a UL subframe 7 can be transmitted in a DLsubframe 1 of a subsequent radio frame, and a PUSCH HARQ-ACK for a ULsubframe 8 can be transmitted in a DL subframe 4 of a subsequent frame.In an example, at least four subframes may occur between an uplinksubframe and a downlink subframe to allow for decoding and processing ofthe downlink transmission, uplink transmission, and/or PHICH.

The dynamic reconfiguration technology (e.g., methods, computercircuitry, nodes, configuration devices, processors, transceivers, orUEs) described herein can provide a dynamic reconfiguration of UL-DL TDDconfigurations with minimum changes to the UE terminal and to the LTEspecification while preserving full flexibility in terms of trafficadaptation capabilities. In addition, the technology may not add newphysical (PHY) layer signaling or change PHY layer signaling to supportfast adaptation time scale in the order of 10 ms.

In an example, the technology may use existing legacy LTE UL-DLconfigurations without adding new UL-DL configurations. Legacy UEs (e.g.LTE Release 8-11 UEs) can operate using semi-static UL-DL configurationbroadcasted in SIB1, so the dynamic reconfiguration has minimal to noimpact on legacy UE behavior. The dynamic reconfiguration technology cansupport a fast adaptation time scale for advanced UEs (e.g., LTE Release12 UEs) without the introduction of additional physical layer signalingand without changes in the LTE PHY physical structure. The dynamicreconfiguration technology can reuse HARQ operation timelines definedfor legacy UEs and preserve flexible traffic adaptation capabilities insmall cells.

The dynamic reconfiguration technology can utilize the flexible subframe(FlexSF) mechanism, as illustrated by FIG. 4. In LTE TDD systems withdynamic UL-DL reconfiguration, the subframes may be classified inaccordance with their possibility to change the transmission directionsbetween legacy LTE UL-DL configurations. For example, subframes 0, 1, 5,and 6 for the 7 legacy LTE UL-DL configurations can be classified asregular (or static) DL subframes (i.e., including DL and specialsubframes) because these subframes may not change from the DLtransmission direction. Subframe 2 for the 7 legacy LTE UL-DLconfigurations can be classified as a regular or static UL subframebecause subframe 2 may not change from the UL transmission direction.Subframes 3, 4, 7, 8, and 9 for the 7 legacy LTE UL-DL configurationscan be classified as flexible because these subframes can be configuredas a DL subframe or an UL subframe (i.e., changed transmission directionfrom DL to UL or UL to DL for the 7 legacy LTE UL-DL configurations)depending on the legacy LTE UL-DL configuration. For example, subframe 3can be configured as an UL subframe for LTE UL-DL configurations 0, 1,3, 4, and 6, or configured as a DL subframe for LTE UL-DL configurations2 and 5. FIG. 4 illustrates the transmission directions of the flexiblesubframes for the 7 legacy LTE UL-DL configurations (i.e., LTE UL-DLconfiguration 0-6).

In another example, the transmission direction of flexible subframesconfigured as UL (i.e., subframes 3, 7, and 8) by UL-DL configuration 1in the SIB1 may be changed to DL for advanced UEs. The dynamicreconfiguration of advanced UEs can imply compliant operation of legacyUEs, since if the legacy UEs are not scheduled or configured fortransmission of the UL signal, the legacy UEs can just skip the ULsubframe. In addition, the dynamic reconfiguration of advanced UEs maynot have an impact on the traffic adaptation characteristics, if aserving cell is configured with a UL favored UL-DL configuration (e.g.,UL-DL configuration 0), since each flexible subframe can dynamicallychange transmission direction from UL to DL and back to UL, asillustrated in FIG. 1.

By default, UEs in the network may follow the legacy behavior inaccordance with the UL-DL configuration broadcasted in the SIB1. If thenetwork determines that dynamic resource allocations (e.g. trafficasymmetry) can improve traffic conditions, the network (e.g., via theeNB) can configure served advanced UEs to operate in dynamic mode thatsupports reconfiguration of the subframe type. Higher layer signaling(e.g., radio resource control (RRC) signaling) or physical layersignaling can be used to activate a dynamic UL-DL configuration mode forthe advanced UEs linked to the cell (e.g., using cell-specificmechanism). Activation of a dynamic UL-DL configuration mode for theadvanced UEs can be performed in UE-specific way so that each advancedUE may be independently configured to start operation in dynamic UL-DLreconfiguration mode. The dynamic UL-DL configuration mode can beactivated using a UL-DL reconfiguration indicator. For instance, the DCI(e.g., a DL DCI grant or an UL DCI grant) or RRC signaling can carry theUL-DL reconfiguration indicator and can be used to activate the dynamicUL-DL reconfiguration mode in a UE specific way. The activation of thedynamic UL-DL reconfiguration mode can be acknowledged by the eNB sothat no ambiguity exists between the eNB and UE in terms of UL/DLoperation in subsequent subframes. ACK/NACK signaling can be used fordynamic UL-DL reconfiguration mode acknowledgements. A legacy UE may notprovide an ACK or may not have capability to provide an ACK.

A default number of DL subframes for a radio frame can be controlled bya UL-DL configuration broadcasted in SIB1. The dynamic UL-DLreconfiguration technology can provide a mechanism for determining whichsubframes can be treated or used as additional DL subframes for advancedUEs with dynamic UL-DL reconfiguration capabilities. In an example, theUL-DL reconfiguration indicator can indicate the set of additionalflexible subframes to be configured as DL subframes using an existingset of UL-DL reconfigurations. For instance, UL favored UL-DLconfiguration 0 can be configured by RRC signaling or the UL favoredUL-DL configuration 0 can be set via the SIB1 or associated with UL-DLconfiguration broadcasted by SIB1, as illustrated in FIG. 5. The DLfavored UL-DL configuration 5 can also be configured by RRC signaling.The UL-DL reconfiguration indicator can configure subframes 4, 7, 8, and9 as DL subframes (e.g., switching transmission direction from UL toDL), which can dynamically change the radio frame from the legacy LTEUL-DL configuration 0 to the legacy LTE UL-DL configuration 4 (206),where subframe 3 is reconfigured 230 from the DL favored UL-DLconfiguration. In another configuration, the DL favored UL-DLconfiguration 5 along with the UL-DL reconfiguration indicator canconfigure subframe 3 as a UL subframe (e.g., switching transmissiondirection from DL to UL), which can dynamically change the radio framefrom the DL favored UL-DL configuration 5 (204) to the legacy LTE UL-DLconfiguration 4 (206). In another example, the UL-DL reconfigurationindicator may not configure subframe 3 as a DL subframe while leavingsubframe 4 as an UL subframe, since the UL-DL configuration does notcorrespond to one of the 7 legacy LTE UL-DL configurations. The UL-DLreconfiguration indicator can be used to dynamically configure theadvanced UE from one legacy LTE UL-DL configuration to another legacyLTE UL-DL configuration without a change in the SIB1.

In another example, the network may use the existing set of legacy LTEUL-DL configurations and instruct the advanced UE to use a DL-favoredUL-DL configuration with a specified number of DL subframes (e.g.,legacy LTE UL-DL configuration 5 (204) in FIG. 5). The DL-favored UL-DLconfiguration may be signaled in a semi-static way (e.g., RRC signaling)and updated non-frequently. Once the advanced UE has been configuredwith the additional DL-favored UL-DL configuration by eNB, the advancedUE can assume that the additional set of DL flexible subframes isavailable for future operations. Thus, the advanced UEs may start tomonitor these flexible subframes for DL grants and allocations of datatransmission. Thus, the UL-favored UL-DL configuration and DL-favoredUL-DL configuration can provide the bounds on the number of flexiblesubframes to monitor for DL grants and allocations of data transmission.For instance, as illustrated in FIG. 5, the UL-favored UL-DLconfiguration can be the legacy LTE UL-DL configuration 0 208 and theDL-favored UL-DL configuration can be the legacy LTE UL-DL configuration5 (204), so all 7 legacy LTE UL-DL configurations can be available fordynamic reconfiguration, and the advanced UE may monitor subframes 3, 4,7, 8, and 9 for DL grants and allocations of data transmission. Inanother example, the UL-favored UL-DL configuration can be the legacyLTE UL-DL configuration 6 and the DL-favored UL-DL configuration can bethe legacy LTE UL-DL configuration 2, so 3 legacy LTE UL-DLconfigurations (i.e., legacy LTE UL-DL configurations 1, 2, and 6) canbe available for dynamic reconfiguration, and the advanced UE maymonitor subframes 3, 4, and 8 for DL grants and allocations of datatransmission. Configuring the UL-favored UL-DL configuration and theDL-favored UL-DL configuration can provide reservation of the “DLflexible subframes”.

A dynamic change of “DL flexible subframes” to UL subframes may usevarious scheduling mechanisms. The DL DCI grants can schedule DL dataallocation for the subframes where DL grants are transmitted. Thus, ifthe eNB determines to use a legacy UL subframe for the DL datatransmission to one of its advanced 12 UEs configured in dynamicoperation mode, the eNB can just schedule DL grant in one of themonitored “DL flexible subframes” (e.g., send a downlink DCI grant).

If the eNB determines to use the “DL flexible subframe” as an ULsubframe, at least two options are available. In an option, the eNB canuse existing DCI messages and allocate a UL grant in one of thepreceding subframes 240 to schedule the UL transmissions in one of the“DL flexible subframes”. For legacy UEs, the “DL flexible subframes” canbe interpreted as UL subframes, as illustrated by legacy LTE UL-DLconfiguration 0 (202) in FIG. 5. For legacy and advanced UEs, the eNBmay use preceding DL subframes for scheduling the UL grant. Thus, theeNB may use the same subframes to allocate UL grant for advanced UEconfigured in dynamic mode or legacy UEs. If an allocated UL grantpoints to one of the “DL flexible subframe” then the UE can interpretthe flexible subframe as a UL subframe and prepare data for futuretransmission at the flexible subframe. An advantage of using existingDCI messages is that UL grants for dynamic mode may not have any changesin the existing DCI messages and may also be implemented using existinglegacy HARQ timelines.

In another option, a new DCI message (e.g., including a UL-DLreconfiguration indicator) may be introduced to indicate that particularDL subframe can be interpreted as a UL and used for UL transmission.Using a new DCI message (e.g., different DCI message type) may define anew HARQ timeline. This DCI message may carry UL-DL configuration to beapplied in the current or the next frame and may be carried out in oneof the static DL subframes. This new UL-DL configuration can be a subsetof legacy UL-DL configurations and may have less number of DL subframescompared to the configured DL-favored UL-DL configuration.

The LTE HARQ timing (or HARQ timeline) can assume asynchronous operationin a DL data transmission and synchronous operation in a UL datatransmission. For instance, a fixed time may exist between a DLscheduling grant and UL HARQ feedback (i.e., DL data transmission);however no strict timing relationship may exist for a DL retransmissionof data. For uplink operation (i.e., UL data transmission), theallocation of a UL grant, a UL transmission, and DL HARQ feedback can bedetermined by strict timing relationships which can depend on the UL-DLconfiguration broadcasted in SIB1.

For network systems with dynamic assignment of UL and DL resources, thelegacy HARQ timelines may be modified, since the subframes maydynamically change transmission direction. Generating new HARQ timelinescan introduce additional complexity at the UE terminal and eNodeB sides.Configuring a terminal (e.g., UE) with UE specific timelines for DL andUL HARQ operation (e.g., reusing legacy HARQ timelines) for the variousdynamically configured LTE UL-DL configurations can remove somecomplexity in the implementation of the HARQ timelines and provide asimpler solution to DL and UL HARQ operation in case of dynamic UL-DLreconfiguration. To enable dynamic UL-DL reconfiguration, for advancedUEs, existing HARQ timelines can be reused by configuring twoindependent HARQ timelines: one HARQ timeline for UL operation 224 andone HARQ timeline for DL operation 212, as illustrated in FIG. 5. TheseUL-DL configurations may be independently configured for each UE in thecell, which can be overlaid on the legacy UL-DL configuration. Theconfiguration of the UL favored and DL favored UL-DL configurations canautomatically change the number of the HARQ processes that are availablefor operation of the advanced UEs. The number of DL HARQ processes maybe defined by the DL favored UL-DL configuration, according to thespecification (e.g., Table 2 (FIG. 3) for the LTE specification). Thenumber of UL HARQ processes may be defined by UL favored UL-DLconfiguration, according to the specification (e.g., Table 4 for the LTEspecification).

In an example, the UL HARQ timeline may be set to a same UL HARQtimeline 224 as defined by the UL-DL configuration transmitted in SIB1for legacy UEs (i.e., the same HARQ timeline may be used for UL HARQoperation). In another example, the DL HARQ timeline may be configuredby higher level signaling (e.g., RRC signaling). FIG. 5 illustrates anexample of a modified HARQ timing operation along with a PUSCHtransmission timing for the case of the UL-favored LTE UL-DLconfiguration 0 and the DL favored LTE UL-DL configuration 5. Forinstance, the DL configured subframes can use the DL favored UL-DLconfiguration for the DL channel timing, such as a PDSCH schedulinggrant transmission timing 210, a PDSCH transmission timing 210, and aPDSCH HARQ feedback timing 212 (e.g., Table 2 (FIG. 3)). The ULconfigured subframes can use the UL favored UL-DL configuration for theUL channel timing, such as a PUSCH scheduling grant timing 220, a PUSCHtransmission timing 222 (e.g., Table 3), a PUSCH HARQ feedback timing224 (e.g., Table 4), and a PUSCH HARQ retransmission timing. For theadvanced UE dynamic UL/DL configuration 206, the DL subframe 5 can usethe DL channel timing 210 and 212, while the UL configured flexiblesubframe 3 can use the UL channel timing 220, 222, and 224. Manydifferent combinations and variations can exist using the principlesillustrated.

FIG. 6. illustrates an example flowchart 300 for an advanced UEs in LTETDD networks that supports the dynamic traffic adaptation. The network(via an eNB) can configure UL favored a UL-DL configuration or a DL/ULbalanced UL-DL configuration (e.g., DL favored UL-DL configuration) froma set of legacy UL-DL configurations 302. The advanced UE (e.g., LTERelease 12 UE) can acquire the UL-DL configuration broadcasted in SIB1(i.e., a legacy UL-DL configuration) 304. The SIB 1 legacy UL-DLconfiguration can be a UL favored UL-DL configuration (relative to otherUL-DL configurations used in the dynamic reconfiguration). The advancedUE can start a normal operation following the HARQ timing timelinesdefined by the legacy UL-DL configuration 306. The network can make adetermination if more DL resources are needed 308. If additional DLresources are not need the advanced UE and the eNB can continue normaloperation (operation 306). If additional resources are needed, the eNBcan activate dynamic UL/DL reconfiguration (e.g., send a UL-DLreconfiguration indicator via RRC signaling or physical layer signaling)310. The eNB can configure the DL and UL favored UL-DL configurationsfrom the set of legacy LTE UL-DL configurations 312. The advanced UE canfollow a new configuration for DL and UL HARQ timelines, and UL legacysubframes designated as DL by a new DL favored UL-DL configuration canbe treated as potential DL subframes 314. The eNB can allocate the ULgrants 316. If the UL grant is allocated, the advanced UE can use the ULHARQ timeline to determine subframe to transmit the UL data (if the ULgrant points to a DL subframe then the subframe type is changed to a DLsubframe). The network can make a determination if the amount of trafficin DL and UL transmission is balanced 318. If the DL and UL traffic isnot balanced, the network and advanced UE can maintain the newconfiguration, as shown by operation 314. If the DL and UL traffic isbalanced, the eNB can deactivate the dynamic UL-DL reconfigurations 320and start over 302.

The dynamic reconfiguration technology described herein can providevarious advantages and benefits to the LTE TDD systems. For example, thetechnology described can enable fast traffic adaptation capabilities bydynamically changing the amount of DL and UL resources. No additionalphysical layer signaling may be needed while still supporting a fast 10ms adaptation time scale, which can provide improved performancebenefits. The technology described can provide legacy (e.g., LTE Release11) compatible operation with dynamic UL-DL reconfiguration for legacyand advanced (LTE Release12 UE or terminals). The technology describedcan reuse existing HARQ timelines with flexible traffic adaptationcapabilities. The technology described may not introduce new UL-DLconfiguration to the LTE system; however, the technology can be extendedto support new UL-DL configurations with some minor changes (e.g., HARQtiming handling).

Another example provides a method 500 for dynamically reconfiguring anuplink-downlink (UL-DL) time-division duplexing (TDD) configuration byan evolved Node B (eNB), as shown in the flow chart in FIG. 7. Themethod may be executed as instructions on a machine, computer circuitry,or a processor for the UE, where the instructions are included on atleast one computer readable medium or one non-transitory machinereadable storage medium. The method includes the operation ofconfiguring a user equipment (UE) using a semi-static UL-DL TDDconfiguration belonging to a set of legacy UL-DL TDD configurations, asin block 510. The next operation of the method can be activating adynamic UL-DL reconfiguration mode when additional DL or UL resourcesare needed for data traffic, as in block 520. The method can furtherinclude dynamically reconfiguring the semi-static UL-DL TDDconfiguration to another legacy UL-DL TDD configuration using a UL-DLreconfiguration indicator to change an UL-DL transmission direction of aflexible subframe (FlexSF), wherein the flexible subframe is capable ofchanging an uplink-downlink transmission direction for a set of legacyUL-DL TDD configurations, as in block 530.

In an example, the operation of dynamically reconfiguring thesemi-static UL-DL TDD configuration to the other legacy UL-DL TDDconfiguration can further include: reconfiguring a DL channel timingbased on a DL favored UL-DL configuration; reconfiguring an UL channeltiming based on a UL favored UL-DL configuration; and communicating aHARQ feedback for subframes in a frame using the DL channel timing orthe UL channel timing respectively. The DL favored UL-DL configurationcan include more DL subframes than a semi-static UL-DL TDD configurationfor the UE, and the DL channel timing can include a physical downlinkshared channel (PDSCH) scheduling grant transmission timing (e.g., 210in FIG. 5), a PDSCH transmission timing (e.g., 210 in FIG. 5), and aPDSCH hybrid automatic repeat request (HARQ) feedback timing (e.g., 212in FIG. 5; Table 2 (FIG. 3)). The UL favored UL-DL configuration caninclude more UL subframes than a semi-static UL-DL TDD configuration forthe UE or is identical to the semi-static UL-DL TDD configurationbroadcasted by the SIB1, and the UL channel timing can include aphysical uplink shared channel (PUSCH) scheduling grant timing (e.g.,220 in FIG. 5), a PUSCH transmission timing (e.g., 222 in FIG. 5; Table3), a PUSCH HARQ feedback timing (e.g., 224 in FIG. 5; Table 4), and aPUSCH HARQ retransmission timing.

In another example, a third generation partnership project (3GPP) longterm evolution (LTE) UL-DL configuration 0 provides the UL favored UL-DLconfiguration for UL-DL configurations 6, 1, 3, 2, 4, and 5. An LTEUL-DL configuration 1 provides the DL favored UL-DL configuration forUL-DL configurations 6 and 0 and the UL favored UL-DL configuration forUL-DL configurations 3, 2, 4, and 5. An LTE UL-DL configuration 2provides the DL favored UL-DL configuration for UL-DL configurations 3,1, 6, and 0 and the UL favored UL-DL configuration for UL-DLconfiguration 5. An LTE UL-DL configuration 3 provides the DL favoredUL-DL configuration for UL-DL configurations 1, 6, and 0 and the ULfavored UL-DL configuration for UL-DL configuration 2, 4, and 5. An LTEUL-DL configuration 4 provides the DL favored UL-DL configuration forUL-DL configurations 3, 1, 6, and 0 and the UL favored UL-DLconfiguration for UL-DL configuration 5. An LTE UL-DL configuration 5provides the DL favored UL-DL configuration for UL-DL configurations 4,2, 3, 1, 6, and 0. An LTE UL-DL configuration 6 provides the DL favoredUL-DL configuration for UL-DL configuration 0 and the UL favored UL-DLconfiguration for UL-DL configuration 1, 3, 2, 4, and 5.

In another configuration, the operation of configuring the UE using thesemi-static UL-DL TDD configuration can further include broadcasting thesemi-static UL-DL TDD configuration to the UE via a system informationblock type 1 (SIB1). In another example, the UL-DL reconfigurationindicator can be indicated using a DL downlink control information (DCI)grant or an UL DCI grant in a DCI grant subframe. The DL DCI grant orthe UL DCI grant can provide a grant for the FlexSF.

In another configuration, the method can further include deactivatingthe dynamic UL-DL reconfiguration mode when the semi-static UL-DL TDDconfiguration is balanced for the data traffic. In another example, theoperation of activating the dynamic UL-DL reconfiguration mode canfurther include: transmitting a dynamic UL-DL reconfiguration modeactivation indicator to the UE to activate a dynamic UL-DLreconfiguration mode, and receiving an acknowledgement (ACK) from the UEindicating that the UE is in the dynamic UL-DL reconfiguration mode. Thedynamic UL-DL reconfiguration mode activation indicator can betransmitted via a DCI or radio resource control (RRC) signaling. Theoperation of deactivating the dynamic UL-DL reconfiguration mode canfurther include: transmitting a dynamic UL-DL reconfiguration modedeactivation indicator to the UE to deactivate the dynamic UL-DLreconfiguration mode; and receiving an acknowledgement (ACK) from the UEindicating the deactivation of the dynamic UL-DL reconfiguration mode bythe UE. The deactivation indicator can be transmitted via a DCI or radioresource control (RRC) signaling. The FlexSF can include subframes 3, 4,7, 8, or 9 configured as UL or DL subframes by the semi-static UL-DL TDDconfiguration.

In another configuration, the operation of dynamically reconfiguring thesemi-static UL-DL TDD configuration to the other legacy UL-DL TDDconfiguration can occur within a duration of approximately one radioframe or approximately 10 milliseconds (ms). The legacy UL-DL TDDconfiguration can include third generation partnership project (3GPP)long term evolution (LTE) UL-DL configurations 0-6. A physical downlinkcontrol channel (PDCCH) or an enhanced PDCCH (EPDCCH) can transmit a DLDCI grant.

Another example provides functionality 600 of computer circuitry on auser equipment (UE) operable for dynamically reconfiguring anuplink-downlink (UL-DL) time-division duplexing (TDD) configuration, asshown in the flow chart in FIG. 8. The functionality may be implementedas a method or the functionality may be executed as instructions on amachine, where the instructions are included on at least one computerreadable medium or one non-transitory machine readable storage medium.The computer circuitry can be receive a UL-DL reconfiguration indicatorfrom a node to dynamically reconfigure a flexible subframe (FlexSF) to adifferent UL-DL transmission direction from a semi-static UL-DLconfiguration, wherein the FlexSF is capable of changing an UL-DLtransmission direction, as in block 610. The computer circuitry can befurther configured to apply a DL channel timing based on a DL favoredUL-DL configuration, wherein the DL favored UL-DL configuration includesmore DL subframes than a semi-static UL-DL TDD configuration for the UE,as in block 620. The computer circuitry can also be configured to applya UL channel timing based on a UL favored UL-DL configuration, whereinthe UL favored UL-DL configuration includes more UL subframes than asemi-static UL-DL TDD configuration for the UE, as in block 630. Inanother example, the computer circuitry can also be configured to applya UL channel timing based on a UL favored UL-DL configuration, whereinthe UL favored UL-DL configuration includes more UL subframes than asemi-static UL-DL TDD configuration for the UE or is identical tosemi-static UL-DL TDD configuration broadcasted by the SIB1.

In an example, the computer circuitry can be further configured tocommunicate a HARQ feedback for subframes in a frame using the DLchannel timing or the UL channel timing. The DL channel timing caninclude a physical downlink shared channel (PDSCH) scheduling granttransmission timing (e.g., a grant can be a DCI carried by the PDCCH orEPDCCH), a PDSCH transmission timing (e.g., can be a same subframe asthe PDSCH scheduling grant), or a PDSCH hybrid automatic repeat request(HARQ) feedback timing (e.g., can be carried in the PUCCH or PUSCH) forsubframes of a frame when the FlexSF is configured as a DL subframe. TheUL channel timing can include a physical uplink shared channel (PUSCH)scheduling grant timing (e.g., a grant can be a DCI carried by the PDCCHor EPDCCH), a PUSCH transmission timing, a PUSCH HARQ feedback timing(e.g., can be carried by a physical hybrid ARQ indicator channel(PHICH)), or a PUSCH HARQ retransmission timing for the subframes of theframe when the FlexSF is configured as a UL subframe.

In another example, the computer circuitry can be further configured to:configure the DL favored UL-DL configuration via radio resource control(RRC) signaling; and configure the UL favored UL-DL configuration viaradio resource control (RRC) signaling, or set the UL favored UL-DLconfiguration to a legacy UL-DL TDD configuration transmitted in asystem information block type 1 (SIB1). In another configuration, thecomputer circuitry can be further configured to: monitor a downlinkcontrol information (DCI) grant subframe for a DL DCI grant or an UL DCIgrant which provides a grant for the FlexSF; configure the FlexSF as theUL subframe when the DCI grant subframe includes the UL DCI grant forthe FlexSF; and configure the FlexSF as the DL subframe when the DCIgrant subframe includes the DL DCI grant for the FlexSF. The UL-DLreconfiguration indicator can be indicated by the grant. The DCI grantsubframe with the DL DCI grant comprises the FlexSF and a physicaldownlink shared channel (PDSCH) is received in the FlexSF. The DCI grantsubframe with the UL DCI grant comprises a DL subframe that precedes theFlexSF, and a physical uplink shared channel (PUSCH) is sent in theFlexSF. A physical downlink control channel (PDCCH) or an enhanced PDCCH(EPDCCH) can be transmitted in the DCI grant subframe.

In another example, a third generation partnership project (3GPP) longterm evolution (LTE) UL-DL configuration 0 provides the UL favored UL-DLconfiguration for UL-DL configurations 6, 1, 3, 2, 4, and 5. An LTEUL-DL configuration 1 provides the DL favored UL-DL configuration forUL-DL configurations 6 and 0 and the UL favored UL-DL configuration forUL-DL configurations 3, 2, 4, and 5. An LTE UL-DL configuration 2provides the DL favored UL-DL configuration for UL-DL configurations 3,1, 6, and 0 and the UL favored UL-DL configuration for UL-DLconfiguration 5. An LTE UL-DL configuration 3 provides the DL favoredUL-DL configuration for UL-DL configurations 1, 6, and 0 and the ULfavored UL-DL configuration for UL-DL configuration 2, 4, and 5. An LTEUL-DL configuration 4 provides the DL favored UL-DL configuration forUL-DL configurations 3, 1, 6, and 0 and the UL favored UL-DLconfiguration for UL-DL configuration 5. An LTE UL-DL configuration 5provides the DL favored UL-DL configuration for UL-DL configurations 4,2, 3, 1, 6, and 0. An LTE UL-DL configuration 6 provides the DL favoredUL-DL configuration for UL-DL configuration 0 and the UL favored UL-DLconfiguration for UL-DL configuration 1, 3, 2, 4, and 5.

In another configuration, the computer circuitry can be furtherconfigured to: receive a dynamic UL-DL reconfiguration mode activationindicator from a node to activate a dynamic UL-DL reconfiguration;activate the dynamic UL-DL reconfiguration mode; and transmit anacknowledgement (ACK) of the dynamic UL-DL reconfiguration mode. Thedynamic UL-DL reconfiguration mode activation indicator can be receivedvia a DCI or radio resource control (RRC) signaling. The computercircuitry can be further configured to: receive a dynamic UL-DLreconfiguration mode deactivation indicator from a node; deactivate thedynamic UL-DL reconfiguration mode; and transmit an acknowledgement(ACK) of the deactivation of the dynamic UL-DL reconfiguration mode. Thedeactivation indicator can be received via a DCI or radio resourcecontrol (RRC) signaling.

In another example, the computer circuitry can be further configured toreceive a semi-static UL-DL TDD configuration belonging to a set oflegacy UL-DL TDD configurations via a system information block type 1(SIB1) prior to receiving the UL-DL reconfiguration indicator. Thecomputer circuitry can dynamically reconfigure the UL-DL TDDconfiguration to another legacy UL-DL TDD configuration within aduration of approximately one radio frame or approximately 10milliseconds (ms). The legacy UL-DL TDD configuration can include thirdgeneration partnership project (3GPP) long term evolution (LTE) UL-DLconfigurations 0-6. The FlexSF can include subframes 3, 4, 7, 8, or 9.

In another configuration, the computer circuitry can be furtherconfigured to: convert a frame of a semi-static UL-DL TDD configurationto another legacy UL-DL TDD configuration based on the received UL-DLreconfiguration indicator; reconfigure a DL channel timing based on theDL favored UL-DL TDD configuration; and reconfigure a UL channel timingbased on the UL favored UL-DL TDD configuration. The DL channel timingcan include a physical downlink shared channel (PDSCH) scheduling granttransmission timing, a PDSCH transmission timing, or a PDSCH hybridautomatic repeat request (HARQ) feedback timing. The UL channel timingcan include a physical uplink shared channel (PUSCH) scheduling granttiming, a PUSCH transmission timing, a PUSCH HARQ feedback timing, or aPUSCH HARQ retransmission timing.

FIG. 9 illustrates an example node 710 (e.g., eNB) and an examplewireless device 720 (e.g., UE). The node can be configured fordynamically reconfiguring an uplink-downlink (UL-DL) time-divisionduplexing (TDD) configuration, as described in 500 of FIG. 7. Referringback to FIG. 9, the node can include a configuration device 712. Theconfiguration device or the node can be configured to communicate withthe wireless device. The configuration device can be configured todynamically reconfigure an uplink-downlink (UL-DL) time-divisionduplexing (TDD) configuration. The configuration device can include aprocessor 714 and a transceiver 716. The processor can be configured todynamically reconfigure a semi-static UL-DL TDD configuration to anotherlegacy UL-DL TDD configuration using a DL DCI grant or an UL DCI grantin a downlink control information (DCI) grant subframe. The DL DCI grantor the UL DCI grant can provide a grant for a flexible subframe(FlexSF). The flexible subframe can be capable of changing anuplink-downlink transmission direction for a set of legacy UL-DL TDDconfigurations. The transceiver can be configured to transmit the DL DCIgrant or the UL DCI grant to a user equipment (UE) in the DCI grantsubframe.

In another configuration, the processor 714 can be further configuredto: apply a DL channel timing based on a DL favored UL-DL configuration;and apply an UL channel timing based on a UL favored UL-DLconfiguration. The DL favored UL-DL configuration can include more DLsubframes than a semi-static UL-DL TDD configuration for the UE, and theDL channel timing can include a physical downlink shared channel (PDSCH)scheduling grant transmission timing, a PDSCH transmission timing, and aPDSCH hybrid automatic repeat request (HARQ) feedback timing. The ULfavored UL-DL configuration can include more UL subframes than asemi-static UL-DL TDD configuration for the UE, and the UL channeltiming can include a physical uplink shared channel (PUSCH) schedulinggrant timing, a PUSCH transmission timing, a PUSCH HARQ feedback timing,and a PUSCH HARQ retransmission timing. The transceiver 716 can befurther configured to communicate a HARQ feedback for subframes in aframe using the DL channel timing or the UL channel timing.

In another example, the processor 714 can be further operable to:activate a dynamic UL-DL reconfiguration mode when additional DLresources are needed for data traffic; and deactivate the dynamic UL-DLreconfiguration mode when the semi-static UL-DL TDD configuration isbalanced for the data traffic. The transceiver 716 can be furtherconfigured to: transmit a dynamic UL-DL reconfiguration mode activationindicator to the UE to activate a dynamic UL-DL reconfiguration mode,where the activation indicator can be transmitted via a DCI or radioresource control (RRC) signaling; receive an acknowledgement (ACK) fromthe UE indicating that the UE activated the dynamic UL-DLreconfiguration mode; transmit a dynamic UL-DL reconfiguration modedeactivation indicator to the UE to deactivate the dynamic UL-DLreconfiguration mode, where the deactivation indicator can betransmitted via a DCI or radio resource control (RRC) signaling; andreceive an acknowledgement (ACK) from the UE indicating the deactivationof the dynamic UL-DL reconfiguration mode by the UE.

The processor 714 can dynamically reconfigure the semi-static UL-DL TDDconfiguration to the other legacy UL-DL TDD configuration within aduration of approximately one radio frame or approximately 10milliseconds (ms). The legacy UL-DL TDD configuration can include thirdgeneration partnership project (3GPP) long term evolution (LTE) UL-DLconfigurations 0-6. The FlexSF can include subframes 3, 4, 7, 8, or 9. Aphysical downlink control channel (PDCCH) or an enhanced PDCCH (EPDCCH)can be transmitted in the DCI grant subframe. The DCI grant subframewith the DL DCI grant can include the FlexSF and a physical downlinkshared channel (PDSCH) can be received in the FlexSF; and the DCI grantsubframe with the UL DCI grant can include a DL subframe that precedesthe FlexSF, and a physical uplink shared channel (PUSCH) can be sent inthe FlexSF.

The node 710 can include a base station (BS), a Node B (NB), an evolvedNode B (eNB), a baseband unit (BBU), a remote radio head (RRH), a remoteradio equipment (RRE), a remote radio unit (RRU), a central processingmodule (CPM).

The wireless device 720 can include a transceiver 724 and a processor722. The wireless device can be configured for dynamically reconfiguringan uplink-downlink (UL-DL) time-division duplexing (TDD) configuration,as described in 600 of FIG. 8.

FIG. 10 provides an example illustration of the wireless device, such asa user equipment (UE), a mobile station (MS), a mobile wireless device,a mobile communication device, a tablet, a handset, or other type ofwireless device. The wireless device can include one or more antennasconfigured to communicate with a node, macro node, low power node (LPN),or transmission station, such as a base station (BS), an evolved Node B(eNB), a baseband unit (BBU), a remote radio head (RRH), a remote radioequipment (RRE), a relay station (RS), a radio equipment (RE), a centralprocessing module (CPM), or other type of wireless wide area network(WWAN) access point. The wireless device can be configured tocommunicate using at least one wireless communication standard including3GPP LTE, WiMAX, High Speed Packet Access (HSPA), Bluetooth, and WiFi.The wireless device can communicate using separate antennas for eachwireless communication standard or shared antennas for multiple wirelesscommunication standards. The wireless device can communicate in awireless local area network (WLAN), a wireless personal area network(WPAN), and/or a WWAN.

FIG. 10 also provides an illustration of a microphone and one or morespeakers that can be used for audio input and output from the wirelessdevice. The display screen may be a liquid crystal display (LCD) screen,or other type of display screen such as an organic light emitting diode(OLED) display. The display screen can be configured as a touch screen.The touch screen may use capacitive, resistive, or another type of touchscreen technology. An application processor and a graphics processor canbe coupled to internal memory to provide processing and displaycapabilities. A non-volatile memory port can also be used to providedata input/output options to a user. The non-volatile memory port mayalso be used to expand the memory capabilities of the wireless device. Akeyboard may be integrated with the wireless device or wirelesslyconnected to the wireless device to provide additional user input. Avirtual keyboard may also be provided using the touch screen.

Various techniques, or certain aspects or portions thereof, may take theform of program code (i.e., instructions) embodied in tangible media,such as floppy diskettes, compact disc-read-only memory (CD-ROMs), harddrives, non-transitory computer readable storage medium, or any othermachine-readable storage medium wherein, when the program code is loadedinto and executed by a machine, such as a computer, the machine becomesan apparatus for practicing the various techniques. Circuitry caninclude hardware, firmware, program code, executable code, computerinstructions, and/or software. A non-transitory computer readablestorage medium can be a computer readable storage medium that does notinclude signal. In the case of program code execution on programmablecomputers, the computing device may include a processor, a storagemedium readable by the processor (including volatile and non-volatilememory and/or storage elements), at least one input device, and at leastone output device. The volatile and non-volatile memory and/or storageelements may be a random-access memory (RAM), erasable programmable readonly memory (EPROM), flash drive, optical drive, magnetic hard drive,solid state drive, or other medium for storing electronic data. The nodeand wireless device may also include a transceiver module (i.e.,transceiver), a counter module (i.e., counter), a processing module(i.e., processor), and/or a clock module (i.e., clock) or timer module(i.e., timer). One or more programs that may implement or utilize thevarious techniques described herein may use an application programminginterface (API), reusable controls, and the like. Such programs may beimplemented in a high level procedural or object oriented programminglanguage to communicate with a computer system. However, the program(s)may be implemented in assembly or machine language, if desired. In anycase, the language may be a compiled or interpreted language, andcombined with hardware implementations.

It should be understood that many of the functional units described inthis specification have been labeled as modules, in order to moreparticularly emphasize their implementation independence. For example, amodule may be implemented as a hardware circuit comprising customvery-large-scale integration (VLSI) circuits or gate arrays,off-the-shelf semiconductors such as logic chips, transistors, or otherdiscrete components. A module may also be implemented in programmablehardware devices such as field programmable gate arrays, programmablearray logic, programmable logic devices or the like.

Modules may also be implemented in software for execution by varioustypes of processors. An identified module of executable code may, forinstance, comprise one or more physical or logical blocks of computerinstructions, which may, for instance, be organized as an object,procedure, or function. Nevertheless, the executables of an identifiedmodule need not be physically located together, but may comprisedisparate instructions stored in different locations which, when joinedlogically together, comprise the module and achieve the stated purposefor the module.

Indeed, a module of executable code may be a single instruction, or manyinstructions, and may even be distributed over several different codesegments, among different programs, and across several memory devices.Similarly, operational data may be identified and illustrated hereinwithin modules, and may be embodied in any suitable form and organizedwithin any suitable type of data structure. The operational data may becollected as a single data set, or may be distributed over differentlocations including over different storage devices, and may exist, atleast partially, merely as electronic signals on a system or network.The modules may be passive or active, including agents operable toperform desired functions.

Reference throughout this specification to “an example” or “exemplary”means that a particular feature, structure, or characteristic describedin connection with the example is included in at least one embodiment ofthe present invention. Thus, appearances of the phrases “in an example”or the word “exemplary” in various places throughout this specificationare not necessarily all referring to the same embodiment.

As used herein, a plurality of items, structural elements, compositionalelements, and/or materials may be presented in a common list forconvenience. However, these lists should be construed as though eachmember of the list is individually identified as a separate and uniquemember. Thus, no individual member of such list should be construed as ade facto equivalent of any other member of the same list solely based ontheir presentation in a common group without indications to thecontrary. In addition, various embodiments and example of the presentinvention may be referred to herein along with alternatives for thevarious components thereof. It is understood that such embodiments,examples, and alternatives are not to be construed as defactoequivalents of one another, but are to be considered as separate andautonomous representations of the present invention.

Furthermore, the described features, structures, or characteristics maybe combined in any suitable manner in one or more embodiments. In thefollowing description, numerous specific details are provided, such asexamples of layouts, distances, network examples, etc., to provide athorough understanding of embodiments of the invention. One skilled inthe relevant art will recognize, however, that the invention can bepracticed without one or more of the specific details, or with othermethods, components, layouts, etc. In other instances, well-knownstructures, materials, or operations are not shown or described indetail to avoid obscuring aspects of the invention.

While the forgoing examples are illustrative of the principles of thepresent invention in one or more particular applications, it will beapparent to those of ordinary skill in the art that numerousmodifications in form, usage and details of implementation can be madewithout the exercise of inventive faculty, and without departing fromthe principles and concepts of the invention. Accordingly, it is notintended that the invention be limited, except as by the claims setforth below.

What is claimed is:
 1. At least one non-transitory machine readablestorage medium having instructions embodied thereon for performingadaptive time division duplexing (TDD) hybrid automatic repeat request(HARQ)-ACKnowledgement (ACK) reporting from a user equipment (UE), theinstructions when executed by one or more processors at the UE performthe following: implementing, at the UE, an adaptive uplink-downlink(UL-DL) configuration received from an eNodeB; processing, at the UE, adownlink (DL) HARQ reference configuration received from the eNodeB fora serving cell, wherein the DL HARQ reference configuration is for theimplemented adaptive UL-DL configuration; and formatting, at the UE,HARQ-ACK feedback for transmission on a physical uplink control channel(PUCCH) or physical uplink shared channel (PUSCH) of the serving cell inaccordance with the DL HARQ reference configuration.
 2. The at least onenon-transitory machine readable storage medium of claim 1, furthercomprising instructions when executed perform the following: performinguplink scheduling and HARQ feedback based on a reference UL-DLconfiguration received from the eNodeB via a system information block(SIB).
 3. The at least one non-transitory machine readable storagemedium of claim 1, wherein the DL HARQ reference configuration isreceived at the UE from the eNodeB via higher layer signaling.
 4. The atleast one non-transitory machine readable storage medium of claim 1,wherein the DL HARQ reference configuration is received at the UE viadedicated signaling from the eNodeB.
 5. The at least one non-transitorymachine readable storage medium of claim 1, wherein the UE is configuredto support adaptive UL-DL configurations based on traffic conditions. 6.An apparatus of a user equipment (UE) operable to perform hybridautomatic repeat request (HARQ)-ACKnowledgment (ACK) operations, theapparatus comprising: memory; and one or more processors configured to:activate, at the UE, an adaptive uplink-downlink (UL-DL) configuration;identify, at the UE, a downlink (DL) HARQ reference configuration for aserving cell, wherein the DL HARQ reference configuration corresponds tothe adaptive UL-DL configuration; and encode, at the UE, adaptive timedivision duplexing (TDD) HARQ-ACK feedback for the serving cell fortransmission to a network node in accordance with the DL HARQ referenceconfiguration.
 7. The apparatus of claim 6, further comprising atransceiver configured to transmit the adaptive TDD HARQ-ACK feedbackfor the serving cell to the network node.
 8. The apparatus of claim 6,wherein the one or more processors are further configured to process theDL HARQ reference configuration received from the network node.
 9. Theapparatus of claim 6, wherein the one or more processors are furtherconfigured to perform uplink scheduling and HARQ feedback based on areference UL-DL configuration received from the network node via asystem information block (SIB).
 10. The apparatus of claim 6, whereinthe DL HARQ reference configuration is received from the network nodevia higher layer signaling.
 11. The apparatus of claim 6, wherein the UEis configured to support adaptive UL-DL configurations based on trafficconditions.
 12. The apparatus of claim 6, wherein the UE includes anantenna, a touch sensitive display screen, a speaker, a microphone, agraphics processor, an application processor, an internal memory, or anon-volatile memory port.
 13. At least one non-transitory machinereadable storage medium having instructions embodied thereon forconfiguring hybrid automatic repeat request (HARQ) referenceconfigurations for a user equipment (UE), the instructions when executedby one or more processors at an eNodeB perform the following:configuring, by the eNodeB, an adaptive uplink-downlink (UL-DL)configuration at the UE; configuring, by the eNodeB, a downlink (DL)HARQ reference configuration for a serving cell at the UE, wherein theDL HARQ reference configuration corresponds to the adaptive UL-DLconfiguration; and processing, at the eNodeB, HARQ-ACKnowledgement (ACK)feedback received from the UE in accordance with the DL HARQ referenceconfiguration.
 14. The at least one non-transitory machine readablestorage medium of claim 13, wherein time division duplexing (TDD)HARQ-ACK feedback is received from the UE in accordance with the DL HARQreference configuration.
 15. The at least one non-transitory machinereadable storage medium of claim 13, wherein the DL HARQ referenceconfiguration is transmitted to the UE via dedicated signaling.
 16. Anapparatus of a network node operable to configure hybrid automaticrepeat request (HARQ)-ACKnowledgment (ACK) operations for a userequipment (UE), the apparatus comprising: memory; and one or moreprocessors configured to: identify, at the network node, a downlink (DL)HARQ reference configuration for a serving cell, wherein the DL HARQreference configuration corresponds to an adaptive UL-DL configurationimplemented at the UE; and process, at the network node, the DL HARQreference configuration for transmission to the UE, wherein the UE isconfigured to perform HARQ-ACKnowledgement (ACK) operations via aphysical uplink control channel (PUCCH) or physical uplink sharedchannel (PUSCH) of the serving cell based on the DL HARQ referenceconfiguration.
 17. The apparatus of claim 16, wherein the HARQ-ACKoperations performed at the UE are time division duplexing (TDD)HARQ-ACK operations.
 18. The apparatus of claim 16, wherein the DL HARQreference configuration is transmitted to the UE via higher layersignaling.
 19. The apparatus of claim 16, wherein the UE is configuredto implement adaptive UL-DL configurations based on traffic conditions.20. The apparatus of claim 16, wherein the network node includes a basestation (BS), a Node B (NB), an evolved Node B (eNB), a baseband unit(BBU), a remote radio head (RRH), a remote radio equipment (RRE), aremote radio unit (RRU), or a central processing module (CPM).